PET FDG Study after Severe Head Injury

Abstract

From a series of 10 patients undergoing PET studies of brain metabolism with ¹⁸Fluo-ro-Desoxy-Glucose (FDG) between 18 days and 62 months after a major head injury 3 chronic cases examined 25, 33 and 62 months after the accident are presented to illustrate some neuroradiologic aspects.

Cortical defects are easily recognised on PET as zones of decreased metabolism after brain laceration corresponding to the residual neurologic deficits. A crossed cerebellar diaschisis is present, reflecting the deafferentation of the cerebellum.

In the patient studied 62 months after a left frontotemporal trauma with subdural hematoma and brain swelling, a good correlation between CT, MR, SPECT and PET was found.

In the third patient with diffuse axonal injury and predominantly left frontal subdural hygroma 33 months before, the brain perfusion looked normal on SPECT and the cerebral metabolism was only mildly reduced in the right frontal and left parieto-occipital regions on PET.

These findings reflect only partially the neuropsychologic sequelae, making the patient unable to work more than 30%. In case of diffuse white matter (and brain stem) injury, the cortical abnormalities shown by PET may not reflect enough the severity of the remaining disability.

Finally two materials used for cranioplasty (Palacos® and BOP®) were tested in vitro before the two patients underwent PET examination. There was no significant attenuation of the radiation in vitro and no distinguishable anomalies over the corresponding hemisphere, like in a third patient without bone flap.